Energizing electron tubes



Patented Apr. 7, 1931 UNITED STATES. PATENT OFFICE DONALD E. WHI'IING, OI BROOKLYN, NEW YORK, ASSIGNOB TO WESTERN ELECTRIC COMPANY, IN GOBPOBATED, OIj' NEW YORK, N. Y., A OORPORATIONQF NEW YORK ENG ELECTRON TUBES Application. filed March 15,

=vice, such as ava'cuum tube filament, and

through a high voltage device, such as a space discharge tube. 1

In the specific form of the invention illustrated in the drawing and described hereinafter, the space currents for tubes of the final stages of a multi-stage amplifier are obtained by rectification and filtration of current from an alternating current source and are com-. bined and passed through the filaments of the first stage or stagesin series to heat those filaments. Moreover, current from the alternating current source lights the filaments of the final stages, and the rectifier and filter supply space current for the first stage or stages of the amplifier. Thus a single alternating current source, rectifier and filter serve I to supply all of the space current and cathode heating current required for the multi-stage amplifie Provision is made, as described hereina er, for preventing the alternating current that beats the, filaments of'the final amplifier output, and also for preventing the alternating components of the plate currents of the final stages-from afiecting the filaments of the first stages.

In the attached drawing Fig. 1 is a circuitdiagram of one form of the invention, and Fig. 2 is a circuit diagram showing a modification of theaportion of the circuit of Fig. 1 to the left of dot-dash line AA. I

Fig. 1 of the drawing shows a three-stage ampllfier arranged for push-pull operation in the last stage. The first stage comprises the tube 1, the second stage comprises the tube 2, and the third stage comprises tubes 3 and 4, all of these tubes being of the three electrode electron discharge type, and preferably, highly evacuated. An interstage transformer 5 couples tubes 1' and 2 and an interstage transformer 6 couples tube 2 to 1924. Serial in. 699,420.

tubes 3 and 4, which are arranged in the so-called push-pull relation. An input transformer 7 couples tube 1 to an incom ing circuit 8, and an output transformer 9 couples tubes 3 and 4 to an outgoing circuit 10.

' The filament's ofthe tubes 2, 3 and 4 are heated by means of alternating current supplied from an alternating current source 15,

through a transformer'lfi, the connectionsfrom the filaments of these tubes to the grid and plate circuits being made at the midpoint of the secondary winding of the transformer 16 after I the fashion disclosed in White Patent No. 1,195,632, August 22, 1.916, in order to reduce the disturbances in circuit due to the alternating currents in the filaments 2, 3 and 4. Since any such disturbances which might originate in the filament of tube 2 wouldappear in circuit'lO in augmented magnitude because'of the amplifica-- tion introduced by tubes 3 and/1, it is especially desirable that the efiect of tube 2 in producing such disturbances be made small. This end canbe furthered by reducing the voltage drop across the filament of the tube 2 to a value at least as low as 1 volt. Therefore, the filament of tube 2 is preferably-a lower voltage filament than the filaments of tubes 3 and 4, equal resistances 20 and 21 being preferably connected in series with the filament of tube 2, one on each side of the filament, in order to give the current through the filament of tube 2 the proper magnitude and still avoid any necessity for special low voltage taps on the secondary winding of transformer 16.

A rectifier 25 supplies the tubes 1, 2, 3 and i 4 with plate current which is smoothed out by means of a filter comprising an inductance 26 and capacities 27 and 28. The rectifier .former 16, to point 36. From the point 35,

. the plate current for tubes 3 and 4 flows through the two halves of the primary winding of transformer 9, from the plates to the filaments of tubes 3 and 4, and through the two halves of the secondary winding of transformer 16 to the point 36. The plate currents for tubes 2, 3 and 4 pass from point 36 i I through the filament of tube 1 and'a variable resistance shunted thereacross,'through an inductance 41, from the plate to the filament of rectifier 25 and to the left hand'end of winding 33. The plate currents of tubes 2, 3 and 4, passin through the filament of tube 1, heat that ament to the proper operating temperature.

The plate current for tube 1 passes from theright hand end of the winding 33 through coil 26, the primary winding of the transformer 5, from the plate to the filament of tube 1, through inductance 41 and rectifier 25, to the left hand end of the winding '33.

It should be noted that capacity 28 is connected in such a manner as to by-pass around the filament of tube 1 the alternating components of the plate currents of the tubes 2, 3 and 4. The inductance 26 servesto prevent these currents -from becoming excessive when overloading occurs in the tubes 3 and 4 and it also improves the push-pull :i'ction. Inductance 41 still further serves to prevent undesirable alternating current from flowing through the filament of tube 1. Inductances 26 and 41 may well be omitted in some cases.

A battery 45 supplies negative potential jor the grids of tubes 2, 3 and 4 and a battery 46 supplies negative potential for the grid of tube 1. However, any other suitable means may, of course, be employed for supplying the proper grid potentials.

Although transformers have been shown for coupling the stages of the amplifier and for coupling he amplifier to the circuits 8 and 10, any other suitable coupling means may be employed- Only three stages of amplifications am shown in Fi 1 of the drawing, but the invention is, 0 course, not limited in this respect. additional amplifier 1', if desired, may, for instance, be inserted between circult 8 and amplifierl, as indicated in Fi 2, with ts plate circuit in parallel to the p ate c1rcu1t of tube 1 and its variable resistance shunt 40', in the lead between the left hand end of shunt 40 and point 48. The function of resistances 40, 40' is to enable any desired portion of the plate currents of tubes 2, 3 and shunted across the plateffilament circuit of tubes 2, 3 and 4 so that the combined value of these supply currents may be less than the filament heating current of tubes 1 and 1'. The resistances 40, 40' and 50 may,'of course, be omitted if so desired.

The tubes 1 and 1' may be low filament current tubes, for instance, of the type commonly known as the U. V.-199, the rated filament current of which is milliamperes. Tubes 3 and 4 may be, forinstance, two tubes of the type known as 205-13. The plate current of two such tubes, when using a plate voltage of,'for instance, 350 volts, is normally about 7 O milliamperes. With the tube of the second stage operating on about 8 milliamperes, for instance, there would then be 78 milliamperes available for heating the filament wruld suflice, in the case of the U. V.-19Q tu e. V 1 a The source 15 may be any suitable A. C. 'source, for instance, an ordinary 110 volt, 60 cycle house lighting circuit. Transformer 16 would then usually step-down the voltage, in the direction from primary to secondary, as would also the windings 32 and 30 of transformer31, the windings 32 and 33 of transformer 31 stepping up the voltage of source 15 to perhaps 400 or 450 volts. Thus approximately 350 volts,for instance, would be available as plate voltage for the tubes, the remainder of the 400 or 450 volts being consumed in the other elements of the space current circuit, such as the rectifier 25 and the coils 26 and 41. For the sake of simplicity,'the drawing shows all of the tubes receiving approximately the same plate voltage, but it is of course to be understood that a plate circuit potentiometer, suchas potentiometer 50' shown in Fig. 2, or other-suitable voltage changing means may be emof tubes 1- and 1', whereas 60 milliamperes ployed to applyi'ny desired part of the available plate voltage toeach of the tubes.

It is pointed out that the transformer 31 should be designed to deliver suflicient voltage to insure that the plate currents used to heat the filament or filaments, such as the filament of tube 1, will be adequate for that purpose. For instance, if either the second or the third stage of theamplifier shown in the drawing be omited, or if only a single amplifying circuit, instead of the two pushpull connected circuits, be used in the third stage, it may in some cases be desirable to increase the plate voltage of at least one stage subsequent to the first stage, In normal opeach filament of the tube 1, 1' at a tempera-.

eration, the D. C. space current from the tubes such as 2, 3 and 4 preferably maintains ture so high that increases of the-temperature would not materially increase the plate current of tubes 1, 1'-that is the tubes 1, 1'

. (as well as each of'the t bes 2, 3 and 4) preftandem connected amplifier stages each de- I vention de liverin an output wave which is a faithful copy 0 the input wave for that stage; or asrepresenting, for example, a detector at 1, and faithfully repeating wave amplifiers at 2, 3 and 4. Where another tube is inserted, ahe'adof'tube 1, in the fashion hereinbefore described, and illustrated in Fig. 2, the additional tube may be, for instance, a faithfully repeating amplifier with tube 1. serving either as a similar amplifier or as a detector; or as isspecifically shown in Fig. 2, may be, for example, a detector with tube 1 serving as a faithfully repeating amplifier; or may he, say, an oscillator, withtube 1 acting, say as a detector. I

As note .above, the rectifier 25-maybe of any suitable type. It is here pointedfout that even where t e, impedance of the rectifier is high compared to that of the filament of tube 1, that filament is heated efliciently, since the PB loss in the circuit through the rectifier and the .filament of tube 1 occurs largely in the space current paths in tubes 2, 3 and 4.

' The general principles herein disclosed may be embodied m many organizations widely different from those illustrated and described,

h ut depgrting from the spirit of the ined in the appended claims. What is claimed is:

- 1. A multi-stage electron tube amplifier circuit, one of said stages having a space .current c rcuit, a precedmg one of said stages having current responsive means for ren-,

dering said preceding stage operative, a d. said circuit comprising means causing sald first means to render said preceding stage operative in response to said space current.

2. In combination, two electrontube 'amplifiers, one of said amplifiers having cathode, means and a heating circuit therefor, the other of said amplifiers having a space current circuit, a source of electromotive force for supplying saidspace current, and means connecting said space current circuit and the first mentioned circuit in serial relation to each other across said source, said cathode means being so proportioned that in normal operation of said amplifiers said spacecurrent heats said cathode means sufficiently to maintain said one amplifier'in the temperature saturation condition. a 's 3. The method of operating a plurality of thermionic am lifiers which comprises maintaining one at t e' temperature saturation condition by energizing it with space current from another.

4. The method of operating two tandem connected thermionic amplifiersone of which includes a push-pull amplifying stage, which comprises maintaining. the cathode means of the other of said amplifiers at itsnormal operating temperature by the combined space current ofa plurality of tubes of said one amplifier. Y v

5. In combination, an electron tube amplifier having thermionic cathode means, an electron .tube amplifier having a space current circuit, a source of alternating current, a

"rectifier, and a circuit including said rectifier,

said cathode means andsaid space current circuit in serial relation to each other across said source, said cathode means being so propo'rtioned as to be maintained at its normal operating temperature by said space current.

6. A multi-stage amplifier system comprising an electron tube amplifier having thermionic cathode means, an electron tube amplifier fed from said thermionic amplifier and having a space current circuit and including' a push-pull stage, a source of alter nating current, a rectifier, and a circuit in. cluding said rectifier, said cathode means and said space current circuit in serial relation t6 each other'across said source, saidcathode means being'so proportioned as to be maint-ained at its normal operating temperature by said space current.

7. In combination, an electron tube ampli--- fier having thermionic cathode means" and having a space current circuit, a second electron tube amplifier having a space current'circuit and having thermionic cathode means, a source of alternatingcurrent, a rectifier, a circuit including said rectifier, said first cathode means and said second space current circuit in serial relation to each other across said source, and means connecting said first spacecurrent circuit across said rectifier and said source.

8. In combination, an electrontube amplifier having thermionic cathode means, a second electron tube having a space current circuit and havin thermionic cathode means, a

source of altern ting current, a rectifier, a circuit including said rectifier, said first cathode -means andsaid space current circuit in serial relation to each other across said source, and

means supplying alternating current from said source to said second cathode means, for heating said seoond'cathode means.

9. 4 In combination, an electron tube amplia fier having thermionic cathode means and having a space current. circuit, a second electron tube having a space current circuit and having thermionic cathode means, a source of alternating current, a rectifier, a circuit including said rectifier, said first cathode means and said second space current circuit in serial relation to each other across said source, means connecting said first space current circuit across said rectifier and said source, and a condenser shunted across said second space current circuit.

10. The combinationset forth in claim 2, and a resistance shunted across said heating circuit. I

11. The combination set forth in claim 2, anda resistance shunted across said space current circuit.

12. In combination, a thermionic electron amplifier tube having a filamentary cathode of such length, cross section and material that the normal operating voltage across the cathodeterminals is at least as low as approximately one volt, a source of alternating current waves, and means for connecting said source of waves to said cathode so as to maintain across said cathode terminals said nor mal voltage for heating said cathode.

13. A multi-stage thermionic amplifier, one of said stages preceding the last including filamentary cathode means, a stage subsequent to, said one stage including filamentary cathbde means, a source of alternating current for heating both of said cathode means and resistances for maintaining the normal filament lighting voltage across said first means at least as low as one volt.

14. In combination, a lurality of discharge tubes one of said tu es having a thermionic cathode, a source of alternating current, means for rectifying saidf'current at a voltage high as compared with the voltage requirements of said cathode, and means for passing the rectified curre'nt serially through said cathode and through the space discharge th'of another of said tubes, said current ing the principal source of energy for heatsaid cathode. p

15. The method of operating a relatively low impedance cathode and a rectifier and a space discharge path each having a relatively high impedance}, which comprises energizing said cathode principally from current passed serially through said rectifier and said discharge path.

16. A ulti-stage electron tube amplifier circuit, one oi thestages preceding the last having a tube with a filamentary cathode of such len h, cross-section and material that the tube is maintained at the temperature saturstion conditionby a filament vol? as low as approximately one volt, the oath es of the tubes in the stages succeeding said. oneflstage being such that said tubes are maintained at the tem rature saturation condition by higher ent voltages, and means for heating the first mentioned cathode comprising source of alternating current of said 10w vo tage;

discharge devices, one of said devices having a filamentary cathode, a thermionic rectifier comprising electrodes within a highly evacuated envelope and means for supplying, from the rectified current of said rectifier,

current for heating said cathode of said one device and space current for said other device, said means comprising a filter for said cathode heating current.

18. A multi-stage electron tube amplifier circuit, one of said stages having a space current circuit, a preceding one of said stages having a thermionic cathode of low impedance compared to that of said space current circuit, a rectifier tube of impedance high compared to that of said cathode and comprising an envelope having therein electrodes with a space current path therebetween, and means for supplying, from the rectified current of saidrectifier, space current for the first mentioned one of said stages and current for heating said cathode, said means comprising a filter for said cathode heating current.

19. In combination, a pluralit of space discharge amplifying devices each having a cathode and an anode, means for roducmg a space current between the cat ode and anode of each of said devices, and a circuit for utilizing the space current of one of said devices 'to apply a unidirectional current to the cathode 0 another of said devices to energize said cathode.

20. In combination, a s ace discharge device having a cathode an anode, mearls for producing a space current between the cathode and anode of said space dischar e device, a second space dischar device aving a cathode an anode, the mentioned s cc discharge device'being connected so as to eed into sai second space discharge device, means for producing under control of the s ace current of said first-mentioned space dischar e device; .a space current between the catho e and anode of said second space discharge device, and means for passing the space current of said second space discharge devicethrough 1 the cathode of said first-mentioned device in series to energize said cathode of said firstmentioned device.

21. In combination, a high frequency receiving circuit comprising a detector and an amplifier, a current supp y set comprising a sourcepf alternating current and a recti er therefor, a resistance in series with said rectifier and said source, and connections from said resistance for supplying late potential to said amplifier and to 'sai filament heating current to said detector.

'22. In combination, a high frequency reeeivin circuit comp a detector and an amplifier a current supp 1 set comprising a 17. A system comprising two electric space,

detector and source of alternating current and a rectifier therefor, a resistance in series with said rectifier andsaid source, and connections from said resistance for supplying plate potential to said amplifier and connections from said resistance for supplying plate potential'of a different value for said detector and filament heating current to said detector.

23. In combination, a high frequency receiving circuit comprising a detector, a power amplifier and an intermediate amplifier, a current supply set comprising a source of alternating current and a rectifier therefor, a resistance/1m series with said rectifier and said source, I and connections from said resistance for supplying plate potential of 7 different values to said amplifiers and to said detectorand filament heatingcurrent to said detector and said intermediate amplifier.

, 24. In combination, a high frequency receiving circuit comprising a detector and a power amplifier and an intermediate amplifier, a current supply set comprising a source of alternating current and a rectifier therefor, I a series circuit including said rectifier, said source, a resistance and the filaments of said detector and intermediate amplifier, and connections from said resistance; for supplying plate potentials of different values to said amplifiers and to said detector. V

25. A high frequency receiving circuit comprising a detector and an amplifier, a

current supply set comprising .a source 'of alternating current and a rectifiertherefor, a resistance in series with said rectifier and said source, and connections from said resistance for supplying plate potentials to said amplifier and to said detector, and filament heating current for said detector.

26, An amplification system. comprising in combination a plurality of electron tubes each having a cathode, an anode an'd a control electrode, an input circuit for each of said .tubes including said cathode and control electrode, an output circuit for each of said tubes including said anode and cathode,

-means interlinking the output circuit of each of said tubes with the input circuit of a succeeding tube, circuit connections to a source of alternating current, means for rectifying said current, a "resistance network, connections including a filter system between said resistance network and said rectifying means, a pair of electron tubes having divided input circuits coupled with the output circuit of the last electron tube'of the series,a series circuit including the cathodes of said first mentioned electron tubes and a portion of said resistance network in shunt with the space discharge path of said pair of electron tubes, connections for heating the cathodes of said pair of electron tubes from alternating current, and

means connected in series with the control.

electrodes of said pair of electron tubes for ing eliminating the hum of alternating current in said receivin' system.

27 An ampli cation system comprising in combination a plurality of electron tubes each having a cathode, an anode and a control electrode, an input circuit for each of said ml tubes including said cathode and control electrode, an output circuit for each of said tubes having divided input circuits cou led with of the the output circuit of the last tu series, a series circuit including the cathodes of said first mentioned electron tubes and a portion of said resistance network in shunt with the space discharge ath of said pair of electron tubes, means gr independently energizing the cathodes of said pairof electron tubes, and connections between said resistance network and the anodes of said first mentioned electron tubes for deriving difierpotentials for the anodes of said first mentioned electron tubes.

28. An amplification system comprising in combination a plurality of electron tubes 'with the output circuit of one tube interlinked with the input circuit of a succeeding 7 tube, each of said tubes having grid filament and plate electrodes and at least one of said tubes having larger power capacity than others of said tubes, a resistance network, connected across the output circuit'of one of said last mentioned tubes, a series circuit including the filament electrodes of a number of said tubes, said series circuit being connected in series with a portion of said resistance network whereby the current supply to said filament electrodes and the output circuit of said tube of larger power capacity is governed by said resistance network.

29. An amplification system comprising in combination a plurality of electron tubes with the output circuit of one tube interlinked with the input circuit of a succeeding tube each of saidtubes having grid, filament and plate electrodes and at least one of said tubes having larger power capacity than the others circuit containing the filament electrodes of the tubes of less power capacity than said first mentioned tube, and a circuit including the plate electrode of said larger power capacity tube connected in series with a portion of said resistance network, said resistance network being shunted across the plate circuit of said larger capacity tube.

of said tubes, a resistance network, a series 30. An amplification system comprising in w 7 combination a plurality of electron tubes with the output circuit of one tube interlinked of one of said tubes'of with the in ut circuit of a succeeding tube, a pair of 'e ectron tubes having their input circuits coupled with the output circuit of said first mentioned tubes each of said tubes having grid, filament and plate electrodes, said pair 'ofelectron tubes having larger power capacity thanfi'gaid first mentioned tubes, an impedance n twork, and a seriescircuit including the aments of said first mentioned tubes in series with a parallel connection between a portion of said impedance network and the plate electrodes of said larger power capacity tubes.

31. An amplification system comprising in combination a pluralit of electron tubes with the output circuit 0 one tube interlinked with the input circuit of a succeeding tube, each of said tubes having grid, filament and plate electrodes and at least one of said tubes having larger power capacity than the others of said tubes, a series circuit containing the filament electrodes of the tubes of less power capacity than said last mentioned tube, saidseries circuit including the plate electrode arger power capacity and a resistance network having a portion thereof connected in shunt with the series circuit including the filament electrodes of the tubes of less power capacity than said last mentioned tube.

32. An amplification system comprising in combination a plurality of electron tubes with the output circuit of one tube interlinked with the input circuit of a succeeding tube, a pair of electron tubes having larger ower' capacity than said first menti'pne electron tubes, each of said tubes having grid, filament and plate electrodes, said pair of electron tubes having a larger power capacity than said first mentioned electron tubes, with the plate electrodes thereof connected in paralel, with respect to the plate current supplg, a resistance network, a series circuit inc u mg the filament electrodes of said first mentioned electron tubes and a portion of said resistance network, and connections between said resistance network and the plate circuits of and pair of larger power capacity electron tubes.

In witness whereof, I hereunto subscribe my name this 13th da of March, A. D. 1924. DON 

